Inspection device for detecting surface faults, and an instrument incorporating such a device

Abstract

For the purpose of detecting the presence of surface flaws in tubular members, the surface to be inspected is first coated with penetrant and any excessive penetrant then removed. A device is then moved along the tubular member until that part of the surface to be inspected is reached, whereafter the device is expanded into abutment with this tubular surface. Penetrant that has entered a surface flaw is transferred to the surface of the device, where it can be made visible and studied, subsequent to having constricted the device and removed it from the tubular member. An instrument is provided which includes the device so as to enable a tubular member to be pre-treated with penetrant and penetrant transferred to the surface of the device.

I claim: 
     
       1. A device for use in detecting surface penetrant containing faults or flaws in the inner surface of a tubular member, the device comprising: a handling device and a tubular shaped body of an elastic material having penetrant absorbent surfaces;   said tubular shaped body being movable by said handling device to an area of the inner surface of said tubular member chosen for inspection, expanded to a state in which the penetrant absorbent surfaces abut the entire inner surface of said tubular member surrounding said penetrant absorbent surfaces, and contracted so as to distance the penetrant absorbent surfaces from the inner surface of said tubular member and removal of said tubular shaped body by said handling device.   
     
     
       2. A device according to claim 1, wherein the absorbent surfaces have a structure which exhibits a large number of minute pits, similar to the configuration of a surface that has been finely ground. 
     
     
       3. A device according to claim 1, wherein the absorbent surfaces are provided on an elastic covering in the form of a casing which is comprised by said body. 
     
     
       4. An instrument for use when detecting surface faults or flaws in tubular members, including the device according to claim 1, wherein the instrument also includes means for delivering penetrant to said area of the inner surface of the tubular member chosen for inspection; and said means is combined with the device to form an inspection probe; said means includes two units which are mutually spaced in the longitudinal direction of the tubular member and which seal the surrounding tubular member such as to form in said tubular member a substantially closed, limited space which can be filled with penetrant; and the inspection probe is movable in the tubular member between a first position in which said area of the inner surface of said tubular member selected for inspection is included between the sealing units, and a second position in which the device is surrounded by said area of the inner surface selected for inspection. 
     
     
       5. An instrument according to claim 4, wherein the inspection probe occupies said first position when a liquid delivery and removal line is connected to the bottom part of the space and an overflow line is connected to the upper part of said space. 
     
     
       6. An instrument according to claim 4, wherein the inspection probe also includes an expandable member with a cover of a liquid-absorbent material; and the inspection probe can be displaced in the tubular member at least to a third position in which said expandable member is surrounded by said area of the inner surface chosen for inspection. 
     
     
       7. An instrument according to claim 6, wherein the expandable member is located between said device and said penetrant delivering means. 
     
     
       8. An instrument according to claim 4, wherein the handling device has the form of a tube or a flexible but rotationally rigid hose and is connected at one end thereof to the inspection probe. 
     
     
       9. A device for use in detecting surface faults or flaws in the inner surface of a tubular member, the device comprising: an elastic body having penetrant absorbent surfaces; said elastic body being movable to an area of the inner surface of said tubular member chosen for inspection, expanded to a state in which the absorbent surfaces abut the inner surface of said tubular member, and contracted so as to distance the absorbent surfaces from the inner surface of said tubular member,   said absorbent surfaces being provided on an elastic covering in the form of a casing which is comprised by said body.   
     
     
       10. An instrument for use in detecting surface faults or flaws in the inner surface of a tubular member, the device comprising: an elastic body having penetrant absorbent surfaces; said elastic body being movable to an area of the inner surface of said tubular member chosen for inspection, expanded to a state in which the absorbent surfaces abut the inner surface of said tubular member, and contracted so as to distance the absorbent surfaces from the inner surface of said tubular member,   means for delivering penetrant to said area of the inner surface of the tubular member chosen for inspection and said means being combined with said elastic body to form an inspection probe;   said means including two units which are mutually spaced in the longitudinal direction of the tubular member and which seal the surrounding tubular member such as to form in said tubular member a substantially closed, limited space which can be filled with penetrant; and   the inspection probe being movable in the tubular member between a first position in which said area of the inner surface of said tubular member selected for inspection is included between the sealing units and a second position in which the device is surrounded by said area of the inner surface selected for inspection.   
     
     
       11. An instrument according to claim 10, wherein the inspection probe occupies said first position when a liquid delivery and removal line is connected to the bottom part of the space and an overflow line is connected to the upper part of said space. 
     
     
       12. An instrument according to claim 10, wherein the inspection probe also includes an expandable member with a cover of a liquid-absorbent material; and the inspection probe can be displaced in the tubular member at least to a third position in which said expandable member is surrounded by said area of the inner surface chosen for inspection. 
     
     
       13. An instrument according to claim 12, wherein the expandable member is located between said device and said penetrant delivering means. 
     
     
       14. An instrument according to claim 10, wherein the inspection probe includes a probe handling device for manoeuvering the inspection probe and the handling device has the form of a tube or a flexible but rotationally rigid hose and is connected at one end thereof to the inspection probe. 
     
     
       15. A device for use in detecting surface penetrant containing faults or flaws in the inner surface of a tubular member, the device comprising: a handling device and an elastic body having penetrant absorbent surfaces;   said elastic body being movable by said handling device to an area of the inner surface of said tubular member chosen for inspection, expanded to a state in which the absorbent surfaces abut the inner surface of said tubular member, and contracted so as to distance the absorbent surfaces from the inner surface of said tubular member and removal of said elastic body by said handling device, said absorbent surfaces being provided on an elastic covering in the form of a casing which is comprised by said body.   
     
     
       16. An instrument for use in detecting surface penetrant containing faults or flaws in the inner surface of a tubular member, the device comprising: a handling device and an elastic body having penetrant absorbent surfaces;   said elastic body being movable by said handling device to an area of the inner surface of said tubular member chosen for inspection, expanded to a state in which the absorbent surfaces abut the inner surface of said tubular member, and contracted so as to distance the absorbent surfaces from the inner surface of said tubular member and removal of said elastic body by said handling device,   means for delivering penetrant to said area of the inner surface of the tubular member chosen for inspection;   said means being combined with the device to form an inspection probe;   said means including two units which are mutually spaced in the longitudinal direction of the tubular member and which seal the surrounding tubular member such as to form in said tubular member a substantially closed, limited space which can be filled with penetrant; and   the inspection probe being movable in the tubular member between a first position in which said area of the inner surface of said tubular member selected for inspection is included between the sealing units, and a second position in which the device is surrounded by said area of the inner surface selected for inspection.   
     
     
       17. An instrument according to claim 16, wherein the inspection probe occupies said first position when a liquid delivery and removal line is connected to the bottom part of the space and an overflow line is connected to the upper part of said space. 
     
     
       18. An instrument according to claim 16, wherein the inspection probe also includes an expandable member with a cover of a liquid-absorbent material; and the inspection probe can be displaced in the tubular member at least to a third position in which said expandable member is surrounded by said area of the inner surface chosen for inspection. 
     
     
       19. An instrument according to claim 18, wherein the expandable member is located between said device and said penetrant delivering means. 
     
     
       20. An instrument according to claim 16, wherein the handling device has the form of a tube or a flexible but rotationally rigid hose and is connected at one end thereof to the inspection probe.